Resource reservation and maintenance for preferred path routes in a network

ABSTRACT

A method implemented by a network element (NE) in a network receiving, by the NE, an advertisement comprising preferred path route (PPR) information describing a path from an ingress NE to an egress NE in the network, the PPR information comprising a PPR identifier (PPR-ID) and an attribute associated with a resource to be reserved on the PPR, transmitting, by the NE, the advertisement comprising the PPR-ID and the attribute associated with the resource to be reserved on the PPR to another NE in the network, and updating, by the NE, a local forwarding database to include the PPR information in association with the egress NE in response to the NE being identified in the PPR information.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of International ApplicationNo. PCT/US2019/025643 filed Apr. 3, 2019, by Futurewei Technologies,Inc., and titled “Resource Reservation and Maintenance for PreferredPath Routes in a Network,” which claims the benefit of U.S. ProvisionalPatent Application No. 62/663,115 filed Apr. 26, 2018 by Uma S.Chunduri, et al., and entitled “Resource Reservations and MaintenanceFor Preferred Paths In The Network Through Routing Protocols,” which areincorporated herein by reference as if reproduced in its entirety.

FIELD OF INVENTION

The present disclosure pertains to the field of preferred path routing.In particular, the present disclosure relates to advertising resourcesthat should be reserved along a preferred path route (PPR) andmonitoring usage statistics of the resources that are reserved on thePPR.

BACKGROUND

In a network implementing source routing, a controller that hasknowledge of a complete topology of the underlying network and canprogram an ingress node of the network with a custom path that certaintraffic has to travel to reach a destination. This custom path may notnecessarily be the shortest path between the ingress node and egressnode. An ingress node in the network may use a separate flowclassification technique ((e.g., a source and/or destination addressesor transport port numbers) to associate certain traffic flow with acustom path.

In a network implementing segment routing (SR), packets are steeredthrough the network using segment identifiers (SIDs) that uniquelyidentify segments in the network. A segment may include one or morenodes, interfaces, and links between two nodes in the network. The SIDsare typically carried in the header of the packet.

Currently there are two data planes that use segment routing toprovision custom paths in a network—Segment Routing (SR) Multi-ProtocolLabel Switching (MPLS) (SR-MPLS) and SR-Internet Protocol (IP) Version 6(IPv6) (SR-IPv6). In SR-MPLS, each segment is encoded as a label, and anordered list of segments are encoded as a stack of labels in the headerof the packet. Similarly, in SR-IPv6, each segment is encoded as an IPv6address within a segment routing header (SRH).

SUMMARY

According to a first aspect of the present disclosure, there is provideda method implemented by a network element (NE) in a network, comprisingreceiving, by the NE, an advertisement comprising preferred path route(PPR) information describing a path from an ingress NE to an egress NEin the network, the PPR information comprising a PPR identifier (PPR-ID)and an attribute associated with a resource to be reserved on the PPR,transmitting, by the NE, the advertisement comprising the PPR-ID and theattribute associated with the resource to be reserved on the PPR toanother NE in the network, and updating, by the NE, a local forwardingdatabase to include the PPR information in association with the egressNE in response to the NE being identified in the PPR information.

In a first implementation of the method according to the first aspect,the attribute includes at least one of a bandwidth required to transmita data packet along the PPR, a burst size permitted to be transmittedalong the PPR, a bounded latency permitted to occur on an NE along thePPR, or a lifetime indicating a time period during which the resource isto be reserved on each NE and/or link of the PPR.

In a second implementation of the method according to the first aspector any preceding implementation of the first aspect, the method furthercomprises deleting, by the NE, the PPR information from the forwardingdatabase in response to determining that a state refresh including thePPR information has not been received by the NE within the time periodduring which the resource is reserved, and removing, by the NE, areservation of the resource on one or more of the NEs or links on thePPR in response to determining that the state refresh including the PPRinformation has not been received by the NE within the lifetime.

In a third implementation of the method according to the first aspect orany preceding implementation of the first aspect, the method furthercomprises receiving a state refresh from at least one of a centralentity of the network or a second NE in the network, wherein the staterefresh comprises the PPR information.

In a fourth implementation of the method according to the first aspector any preceding implementation of the first aspect, the method furthercomprises receiving, by the NE, a modification of the attributeassociated with the resource reserved on the PPR from at least one of acentral entity of the network or a second NE in the network, andupdating, by the NE, the local forwarding database based on themodification of the attribute received.

In a fifth implementation of the method according to the first aspect orany preceding implementation of the first aspect, the method furthercomprises determining, by the NE, that at least one NE or link on thePPR fails to satisfy the attribute defined by the PPR information.

In a sixth implementation of the method according to the first aspect orany preceding implementation of the first aspect, the method furthercomprises transmitting a node status to at least one other NE in thenetwork using an underlying Interior Gateway Protocol (IGP) of thenetwork, wherein the node status indicates whether the resource has beensuccessfully reserved based on the attribute included in the PPRinformation.

In a seventh implementation of the method according to the first aspector any preceding implementation of the first aspect, the method furthercomprising transmitting a node status to a central entity of thenetwork, wherein the reservation status indicates whether the resourcehas been successfully reserved based on the attribute included in thePPR information.

In an eighth implementation of the method according to the first aspector any preceding implementation of the first aspect, the method furthercomprising periodically collecting, by the NE, usage statisticsdescribing network characteristics along the PPR after reserving theresource for the PPR based on the PPR information.

In a ninth implementation of the method according to the first aspect orany preceding implementation of the first aspect, the method furthercomprising transmitting, by the NE, the usage statistics to at least oneother NE in the network using an underlying Interior Gateway Protocol(IGP) of the network.

In a tenth implementation of the method according to the first aspect orany preceding implementation of the first aspect, the method furthercomprising transmitting, by the NE, the usage statistics directly to acentral entity of the network.

In an eleventh implementation of the method according to the firstaspect or any preceding implementation of the first aspect, wherein theusage statistics comprises at least one of a queue delay that occurs asa plurality of data packets are transmitted from the NE to the other NEon the PPR or bandwidth statistics regarding at least one link coupledto the NE.

In a twelfth implementation of the method according to the first aspector any preceding implementation of the first aspect, wherein thebandwidth statistics comprises at least one of a utilized bandwidth, andunutilized bandwidth, or a bandwidth violation.

In a thirteenth implementation of the method according to the firstaspect or any preceding implementation of the first aspect, wherein thePPR is a shortest path between the source and the destination, andwherein the PPR information only includes the attribute associated withthe resource to be reserved on the PPR to another NE in the network.

In a fourteenth implementation of the method according to the firstaspect or any preceding implementation of the first aspect, wherein thePPR is determined based on a network characteristic requested by thesource.

In a fifteenth implementation of the method according to the firstaspect or any preceding implementation of the first aspect, wherein theadvertisement is received from at least one of a second NE in thenetwork or a central entity of the network.

In a sixteenth implementation of the method according to the firstaspect or any preceding implementation of the first aspect, wherein thePPR-ID is at least one of a Multi-Protocol Label Switching (MPLS) label,a segment identifier (SID), an Internet Protocol (IP) version 4 (IPv4)address, or an IP version 6 (IPv6) address.

According to a second aspect of the present disclosure, there isprovided a method implemented by a first NE in a network. The methodcomprises receiving, by the first NE, an advertisement comprisingpreferred path route (PPR) information from a second NE in the network,the PPR information describing a path from an ingress NE to an egress NEin the network, the PPR information comprising a PPR identifier (PPR-ID)and an attribute associated with a resource to be reserved on the PPR,updating, by the first NE, the local forwarding database to include thePPR information in association with the egress NE in response to thefirst NE being identified in the PPR information, provisioning, by thefirst NE, the PPR according to the attribute associated with theresource to be reserved on the PPR, updating, by the first NE, a nodestatus associated with the first NE in response to provisioning the PPRaccording to the attribute, and transmitting, by the first NE, the nodestatus to a central entity of the network.

According to a third aspect of the present disclosure, there is providedan NE in a network. The NE comprises a receiver configured to receive anadvertisement comprising preferred path route (PPR) informationdescribing a path from an ingress NE to an egress NE in the network, thePPR information comprising a PPR identifier (PPR-ID) and an attributeassociated with a resource to be reserved on the PPR, a transmittercoupled to the processor and configured to transmit the advertisementcomprising the PPR-ID and the attribute associated with the resource tobe reserved on the PPR to another NE in the network, and a processorcoupled to the receiver and configured to update a local forwardingdatabase to include the PPR information in association with the egressNE.

According to a fourth aspect of the present disclosure, there isprovided a non-transitory medium configured to store a computer programproduct comprising computer executable instructions that, when executedby a processor of a network element (NE) implemented in a network, causethe processor to receive an advertisement comprising preferred pathroute (PPR) information describing a path from an ingress NE to anegress NE in the network, the PPR information comprising a PPRidentifier (PPR-ID) and an attribute associated with a resource to bereserved on the PPR, transmit the advertisement comprising the PPR-IDand the attribute associated with the resource to be reserved on the PPRto another NE in the network, and update a local forwarding database toinclude the PPR information in association with the destination inresponse to the NE being identified in the PPR information.

According to a fifth aspect of the present disclosure, there is providedan apparatus comprising a means for receiving an advertisementcomprising preferred path route (PPR) information describing a path froman ingress NE to an egress NE in the network, the PPR informationcomprising a PPR identifier (PPR-ID) and an attribute associated with aresource to be reserved on the PPR, a means for transmitting theadvertisement comprising the PPR-ID and the attribute associated withthe resource to be reserved on the PPR to another NE in the network, anda means for updating a local forwarding database to include the PPRinformation in association with the destination.

For the purpose of clarity, any one of the foregoing embodiments may becombined with any one or more of the other foregoing embodiments tocreate a new embodiment within the scope of the present disclosure.

These and other features will be more clearly understood from thefollowing detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is nowmade to the following brief description, taken in connection with theaccompanying drawings and detailed description, wherein like referencenumerals represent like parts.

FIG. 1 is a diagram illustrating a network configured to implementpreferred path routing according to various embodiments of thedisclosure.

FIG. 2 is a diagram illustrating the network including NEs configured toimplement resource reservation and maintenance according to variousembodiments of the disclosure.

FIG. 3 is an embodiment of an NE in the network configured to implementpreferred path routing according to various embodiments of thedisclosure.

FIGS. 4A-C are diagrams illustrating an example of a node resourcecapability sent by an NE in the network, and fields within the noderesource capability, according to various embodiments of the disclosure.

FIG. 5A is a diagram illustrating an example of an advertisement thatincludes PPR information according to various embodiments of thedisclosure.

FIG. 5B is a diagram illustrating examples of the attributes carried inthe PPR information describing a PPR according to various embodiments ofthe disclosure.

FIGS. 6A-D are diagrams illustrating examples of the attributesdescribed in FIG. 5B according to various embodiments of the disclosure.

FIGS. 7A-D are diagrams illustrating an example of a node status sent byan NE on the PPR, and fields within the node status, according tovarious embodiments of the disclosure.

FIGS. 8A-C are diagrams illustrating an example of usage statisticscollected by NEs on the PPR, and fields within the usage statistics,according to various embodiments of the disclosure.

FIG. 9 is a method for implementing resource reservation and maintenanceon a PPR according various embodiments of the disclosure.

FIG. 10 is another method for implementing resource reservation andmaintenance on a PPR according various embodiments of the disclosure.

FIG. 11 is an apparatus for implementing resource reservation andmaintenance on a PPR according various embodiments of the disclosure.

FIG. 12 is another apparatus for implementing resource reservation andmaintenance on a PPR according various embodiments of the disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrativeimplementation of one or more embodiments are provided below, thedisclosed systems and/or methods may be implemented using any number oftechniques, whether currently known or in existence. The disclosureshould in no way be limited to the illustrative implementations,drawings, and techniques illustrated below, including the exemplarydesigns and implementations illustrated and described herein, but may bemodified within the scope of the appended claims along with their fullscope of equivalents.

Source routing mechanisms, such as segment routing, have been definedfor MPLS and IPv6 data planes. However, existing source routingmechanisms do not enable paths to be provisioned based on trafficengineering (TE) parameters such that the provisioned paths satisfycertain Quality of Service (QoS) parameters. In addition, existing pathprovisioning protocols do not include mechanisms by which to monitor theusage of various resources on the provisioned path such that the pathcan be re-provisioned if the path no longer satisfies the QoSparameters.

Disclosed herein are various embodiments directed to reserving resourceson a Preferred Path Route (PPR) (also referred to herein as a “preferredpath” or a “PPR path”) between a source and a destination based onattributes defining a TE parameter or a network characteristic of thePPR. In an embodiment, a network element (NE) in a network sends anadvertisement that includes PPR information describing a PPR to otherNEs in the network. The PPR information includes a PPR-identifier (ID)identifying the PPR and one or more attributes related to the resourcethat should be reserved on the PPR. After the resources have beensuccessfully reserved on the PPR, NEs on the PPR monitor the usage ofthe resources on the PPR to collect usage statistics describing used orunused resources on the PPR. The NEs on the PPR send the usagestatistics to a central entity of the PPR. In this way, the embodimentsdisclosed herein enable a mechanism to provision PPRs that satisfy QoSparameters based on attributes specified for the PPRs and a mechanism tomonitor the resources reserved on the PPRs.

FIG. 1 is a diagram illustrating a network 100 (also referred to hereinas a “domain or “subnetwork”) configured to implement preferred pathrouting according to various embodiments of the disclosure. The network100 comprises a source 170, a destination 180, a central entity 175(also referred to herein as a “controller”), two areas 150A and 150B,and central entity-to-area links 136-137. The source 170 is connected tonetwork 100 via a source-to-domain link 140, and the destination isconnected to network 100 via a destination-to-domain link 141.

In an embodiment, the central entity 175 may be a network or domaincontroller that maintains a topology of the network 100 to craft paths(both shortest paths 145 and PPRs 120) between edge NEs 101-112 in thenetwork 100, as will be further described below. In an embodiment, thecentral entity is substantially similar to a Path Computation Element(PCE), which is further described in Internet Engineering Task Force(IETF) Request for Comments (RFC) 8281, entitled “Path ComputationElement Communication Protocol (PCEP) Extensions for PCE-Initiated LSPSetup in a Stateful PCE Model,” by E. Crabbe, dated December 2017. In anembodiment, the central entity 175 may be substantially similar to aSoftware Defined Network Controller (SDNC), which is further describedin the IETF RFC 8402 entitled “Segment Routing Architecture,” by C.Filsfils, dated July 2018. In an embodiment, the central entity 175 maybe substantially similar to an Application Layer Traffic Optimization(ALTO) server, which is further described in the IETF RFC 7285, entitled“Application Layer Traffic Optimization (ALTO) Protocol,” by R. Alimi,dated September 2014.

Areas 150A-B are subnetworks within the network 100 that may beassociated with a specific geographic area or building. Each of areas150A-B may be operated by a different operator or service provider. Asshown by FIG. 1, area 150A comprises elements 101-107 and 122-128 (e.g.,NEs 101-107 interconnected by links 122-128). Area 150B compriseselements 106-112 and 128-135 (e.g., NEs 106-112 interconnected by links128-135). As shown by FIG. 1, areas 150A-B both share two NEs 106-107and link 128. NEs 106-107 and link 128 may be configured to operatewithin both areas 150A-B using a packet forwarding protocol implementedby both areas 150A-B.

In an embodiment, NEs 101-112 (also referred to herein as “nodes”) maybe a topological devices (or physical devices) such as a router, abridge, a network switch, or a logical device configured to performswitching and routing using the preferred path routing mechanismsdisclosed herein. In an embodiment, one or more of the NEs 101-112 maybe non-topological NEs such as, for example, a function, context,service, or a virtual machine.

In an embodiment, NEs 101-112 may be headend nodes or edge nodespositioned at an edge of the network 100. For example, NE 101 may be aningress node at which packets are received (either from a source oranother NE from another network/domain), and NE 110 may be an egressnode from which traffic is transmitted (either to a destination oranother NE in another network/domain). While NEs 101-112 are shown inFIG. 1 as headend nodes, it should be appreciated that NEs 101-112 mayotherwise be an intermediate node or any other type of NE. Although onlytwelve NEs 101-112 are shown in FIG. 1, it should be appreciated thatthe network 100 shown in FIG. 1 may include any number of NEs.

In an embodiment, the central entity 175 and NEs 101-112 are configuredto implement various packet forwarding protocols, such as, but notlimited to, Multi-Protocol Label Switching (MPLS), Segment Routing-MPLS(SR-MPLS), Internet Protocol (IP) Version 4 (IPv4), IP Version 6 (IPv6),Next Generation Explicit Routing (NGER), or Big Packet Protocol. In anembodiment, each area 150A and 150B may be configured to implement adifferent packet forwarding protocol. For example, NEs 101-107 in area150A are configured to implement MPLS, while NEs 106-112 in area 150Bare configured to implement IPv6. In such an embodiment, NEs 106 and107, which are shared between the two areas 150A-B, may be configured toimplement both packet forwarding protocols to ensure proper datatransmission between areas 150A-B.

The links 122-135 may be wired or wireless links or interfacesinterconnecting the NEs 101-112 together. The central entity-to-arealinks 136-137 are also wired or wireless links or interfacesinterconnecting at least one of the NEs 101-112 within an area 150A-B tothe central entity 175. As described above, the source 170 is connectedto network 100 via a source-to-domain link 140, and the destination isconnected to network 100 via a destination-to-domain link 141. Thesource-to-domain link 140 and the destination-to-domain link 141 may bewired or wireless links or interfaces interconnecting each of the source170 and the destination 180 to an NE 101 and NE 110, respectively, ofthe network 100.

In operation, the central entity 175 is configured to determine one ormore shortest paths 145 between two edge NEs 101-112 in the network 100and one or more PPRs 120 between two edge NEs 101-112 in the network100. A shortest path 145 refers to a path between two NEs 101 and 110(ingress NE 101 and egress NE 110) or between a source 170 anddestination 180 that is determined based on a metric, such as, forexample, a cost or weight associated with each link on the path, anumber of NEs on the path, a number of links on the path, etc. In anembodiment, a shortest path 145 may be computed for a destination usinga Dijkstra's Shortest Path First (SPF) algorithm.

A PPR 120 (also referred to herein as a Non-Shortest Path (NSP)) refersto a custom path or any other path that is determined based on anapplication or server request for a path between an ingress NE 101 andan egress NE 110 or between a source 170 and destination 180. In anembodiment, the PPR 120 deviates from the shortest path 145. However,the PPR 120 may also be the same as the shortest path 145 in somecircumstances.

In an embodiment, the central entity 175 is configured to determine thePPR 120 based on attributes specified for the PPR 120. As will befurther described below, an attribute specified for the PPR 120 may beone or more TE parameters, network characteristics, or servicerequirements that are associated with a resource to be reserved on thePPR 120. In an embodiment, the attribute may include a bandwidthrequirement, a maximum burst size, a latency requirement, a minimumjitter, a minimum error rate, a required throughput, etc. In anembodiment, reserving resources on the NEs 101-112 and links 122-135 ofthe PPR 120 according to the attributes specified for the PPR 120ensures that data packets being transmitted along the PPR 120 satisfy acertain QoS parameter set by the source 170 of the PPR 120 or anoperator of the network 100.

In an embodiment, a source 170, or an ingress NE 101, transmits arequest to the central entity 175 to compute a PPR 120 between thesource 170 and the destination 180 (or between the ingress NE 101 andthe egress NE 110) according to a particular attribute. In anotherembodiment, the attributes for a particular PPR 120 may be preconfiguredat the central entity 175 by an operator or service provider of thenetwork 100. In another embodiment, the central entity 175 is configuredto determine the PPR 120 according to the attribute requested.

The PPRs 120 and the shortest paths 145 may each comprise a sequentialordering of one or more elements 101-112 and 122-135 (e.g., NEs 101-112and links 122-135) in the network 100. As shown in FIG. 1, the shortestpath 145 between ingress NE 101 and egress NE 110 includes the followingelements: NE 101, link 122, NE 102, link 123, NE 103, link 127, NE 107,link 130, NE 108, link 131, NE 109, link 132, and NE 110. As describedabove, the shortest path 145 between ingress NE 101 and egress NE 110 isbased on metrics of each of the elements 101-112 and 122-135 in thenetwork 100.

In contrast, the PPR 120 between ingress NE 101 and egress NE 110includes the following elements: NE 101, link 124, NE 104, link 125, NE105, link 126, NE 106, link 135, NE 112, link 134, NE 111, link 133, andNE 110. In an embodiment, the central entity 175 determines the elementson the PPR 120 based on an attribute, such as, bandwidth, latency, orburst size, of each of one or more of the elements (NE 101, link 124, NE104, link 125, NE 105, link 126, NE 106, link 135, NE 112, link 134, NE111, link 133, and NE 110) on PPR 120.

After the central entity 175 determines the PPR 120 based on theattribute, the central entity 175 transmits PPR information describingthe PPR 120 to a headend or ingress NE 101-112 in each area 150A-B ofnetwork 100. For example, the central entity 175 transmits PPRinformation describing the PPR 120 implemented in area 150A to NE 103via central entity-to-area link 136. Similarly, the central entity 175transmits PPR information describing the PPR 120 implemented in area150B to NE 110 via link 137.

In an embodiment, the PPR information includes information thatdescribes the PPR 120. The PPR information may include, for example, aPPR-ID identifying the PPR 120. In an embodiment, the PPR-ID includes asingle label, address, or ID identifying the PPR 120. For example, whenthe network 100 implements SR-MPLS, the PPR-ID may be an MPLS label oran SID identifying a PPR. When the network 100 implements IPv6, thePPR-ID may be an IPv6 SID identifying a PPR. When the network 100implements IPv4, the PPR-ID may be an IPv4 address or prefix identifyinga PPR. Similarly, when the network 100 implements IPv6, the PPR-ID maybe an IPv6 address or prefix identifying a PPR.

The PPR information also includes multiple PPR-path description elements(PDEs) describing one or more elements (NE 101, link 124, NE 104, link125, NE 105, link 126, NE 106, link 135, NE 112, link 134, NE 111, link133, and NE 110) or segments including one or more of the elements onthe PPR 120. In an embodiment, each of the PPR-PDEs includes a label,address, or identifier of one or more of the elements 101, 124, 104,125, 105, 126, 106, 135, 112, 134, 111, 133, and 110 or segmentsincluding one or more of the elements on the PPR 120. In an embodiment,the PPR-PDEs include a sequential ordering of MPLS labels, IPV6addresses, or IPv4 addresses that specify the actual path (e.g., one ormore of the elements 101, 124, 104, 125, 105, 126, 106, 135, 112, 134,111, 133, and 110 on the PPR 120) toward a destination address of theegress NE 110 or the destination 180 (also referred to herein as a“prefix”). In an embodiment, each of the PPR-PDEs may also definewhether the element being described is a topological NE or anon-topological NE.

In various embodiments, two types of PPRs 120 may be described by thePPR-PDEs, a strict PPR 120 and a loose PPR 120. In a strict PPR 120,every single NE (NE 101, NE 104, NE 105, NE 106, NE 112, NE 111, and NE110) along the PPR 120 is specified or described in its own PPR-PDE. Ina loose PPR 120, certain elements 101, 124, 104, 125, 105, 126, 106,135, 112, 134, 111, 133, and 110 (also referred to herein as “hops”)along a PPR 120 may be skipped such that only a subset of the elements101, 124, 104, 125, 105, 126, 106, 135, 112, 134, 111, 133, and 110along a PPR 120 is specified or described in its own PPR-PDE. When loosePPRs 120 are described by the PPR-PDEs, the NEs along the path useshortest path routing in between elements that are not explicitlyspecified in a PPR-PDE (i.e., to reach the next topological PDE of theloose PPR 120).

The PPR information may include several other descriptive elements,which are further described in Patent Cooperation Treaty (PCT)Application No. PCT/US2019/015419, entitled “Advertising and ProgrammingPreferred Path Routes using Interior Gateway Protocols,” by UmaChunduri, et. al., and filed on Jan. 28, 2019 (hereinafter referred toas the “PPR Patent”). For example, the PPR information may include a PPRtype, defining an encoding scheme used to encode the PPR-ID. Forexample, when the PPR-ID is an IPv4 address, then the PPR type is avalue indicating that the PPR-ID is an IPv4 address. Similarly, when thePPR-ID is an IPv6 address or an MPLS label, then the PPR type is a valueindicating that the PPR-ID is an IPv6 address or an MPLS label. The PPRinformation may also include various flags. For example, one bit mayindicate whether all the NEs in the network 100 downloads the PPRinformation or only a subset of the NEs identified in the PPR-PDEsdownloads the PPR information.

In an embodiment, the PPR information may also include one or moreattributes associated with a resource to be reserved on the PPR 120. Asdescribed above, the attribute refers to a TE parameter networkcharacteristic that should be satisfied when reserving a resource on thePPR 120. Examples of attributes specified for a PPR 120 may includebandwidth, burst size, latency, and lifetime, which will be furtherdescribed below with reference to FIGS. 5A-B and 6A-D.

After receiving the PPR information, NEs 103 and 110 first determinewhether the NEs 103 and 110 are identified in a PPR-PDE of the PPRinformation. When a PPR-PDE does not identify the NE 103 or 110, NEs 103and 110 ignore the PPR information. In contrast, when a PPR-PDEidentifies the NE 103 or 110, the NE 103 or 110 updates a localforwarding database to include an entry including the PPR informationfor a destination address corresponding to the egress NE 110 or thedestination 180.

In an embodiment, the local forwarding database is updated by addinganother entry for a particular destination ID or address of the egressNE 110 or the destination 180. The new entry includes at least one ofthe PPR-ID, each of the PPR-PDEs corresponding the PPR-ID, an ID oraddress of the next element 101, 124, 104, 125, 105, 126, 106, 135, 112,134, 111, 133, or 110 on the PPR 120 to which to forward a data packet,and the one or more attributes specified for the PPR 120. In anotherembodiment, NEs 103 and 110 are configured to update the localforwarding database to include the PPR information relative to adestination address of the egress NE 110 or the destination 180regardless of whether the NE 103 or 110 is identified in a PPR-PDE ofthe PPR information.

After receiving the PPR information and updating a local forwardingdatabase, the NEs 103 and 110 send (or flood) an advertisement includingthe PPR information to all of the other NEs 101-112 in the respectivearea 150A-B of network 100 using the underlying Interior GatewayProtocol (IGP) of the respective area 150A-B. The advertisementincluding the PPR information may be encoded and flooded through therespective area 150A-B using an IGP, such as, for example, Open ShortestPath First (OSPF) Version 2 (OSPFv2), OSPF Version 3 (OSPFv3),Intermediate System-Intermediate System (IS-IS), or direct SDN. Forexample, after receiving the PPR information, the NE 103 transmits (orfloods) the PPR information to NEs 101-102 and 104-107 in area 150Aaccording to the IGP implemented by area 150A. Similarly, afterreceiving the PPR information, NE 110 transmits (or floods) the PPRinformation to NEs 106-109 and 111-112 in area 150B according to the IGPimplemented by area 150B.

In an embodiment, each of the receiving NEs 101-102, 104-107, 106-109,and 111-112 determines whether the receiving NE 101-102, 104-107,106-109, or 111-112 is identified in a PPR-PDE of the PPR information.In an embodiment, when a PPR-PDE identifies the receiving NE 101-102,104-107, 106-109, or 111-112, the receiving NE 101-102, 104-107,106-109, or 111-112 updates a local forwarding database to include anentry including the PPR information for a destination addresscorresponding to the egress NE 110 or the destination 180. In thisembodiment, when a PPR-PDE does not identify the receiving NE 101-102,104-107, 106-109, or 111-112, the receiving NE 101-102, 104-107,106-109, or 111-112 ignores the PPR information. In another embodiment,each of the receiving NEs 101-102, 104-107, 106-109, and 111-112 updatesa local forwarding database to include an entry including the PPRinformation regardless of whether the NE is identified in a PPR-PDE.

The embodiments disclosed herein are directed to advertising andprogramming one or more attributes defining network characteristicsrelated to a resource to be reserved on the PPR 120 along with the basicPPR information (e.g., PPR-ID and PPR-PDEs). As the NEs 101-112 receivethe PPR information including the PPR-ID, PPR-PDEs, and the attributes,the NEs 101-112 update the local forwarding databases and thereby becomeprogrammed to construct the PPR 120 based on the attributes defined bythe PPR information. In this way, the PPR 120 is constructed to ensurethat the PPR 120 satisfies QoS parameters defined using the attributesincluded in the PPR information.

In an embodiment, preferred path routing is extended to indicate theresources (e.g., attributes) to be reserved along the PPR. The resourcesindicated are not only for providing a committed bandwidth ordeterministic latency, but also for assuring an overall service levelguarantee on the network 100. In an embodiment, reservations areincluded in the PPR information in terms of required resources(bandwidth), traffic characteristics (burst size), and service levelparameters (expected maximum latency at each hop) based on thecapabilities of each element on the PPR 120.

FIG. 2 is a diagram illustrating the network 100 configured to implementpreferred path routing according to various embodiments of thedisclosure. As shown by FIG. 2, the NEs 101-112 within the areas 150A-Bof the network 100 exchange data with another to reserve resources alonga PPR 120 and monitor the resources along the PPR 120. The data that canbe exchanged includes a node resource capability 203, PPR information210, a node status 220, and usage statistics 215. It should beappreciated that other data relevant to the PPR 120 may be exchangedamong NEs 101-112 within the areas 150A-B of the network 100 for thepurpose of reserving and monitoring resources along the PPR 120.

First, each NE 101-112 within the network 100 advertises a node resourcecapability 203 to all of the other NEs 101-112 within a respective area150A-B to indicate that the NE 101-112 is located using the underlyingIGP. For example, NE 101 sends a node resource capability 203 to NEs102-107 in area 150A, and NE 106 sends a node resource capability 203 toNEs 107-112 in area 150B. In an embodiment, the node resource capability203 is flooded to other NEs 101-112 in the network 100 before the PPRinformation 210 is flooded to other NEs 101-112 in the network 100.

In an embodiment, the node resource capability 203 is sent to thecentral entity 175 via central entity-to-area links 136-137 periodicallyor through any other offline mechanism. For example, supposing that NE103 is a Border Gateway Protocol (BGP) Link State (BGP-LS) speaker, NE103 may transmit the node resource capability 203 to the central entity175. In an embodiment, the node resource capability 203 is encodedaccording to BGP-LS Prefix Network Layer Reachability Information (NLRI)when the node resource capability 203 is transmitted to the centralentity 175.

A node resource capability 203 is a message sent by each NE 101-112within a network 100 that indicates various capabilities of the NE101-112 sending the node resource capability 203. In an embodiment, thenode resource capability 203 is provisioned by a central entity 175 andflooded to other NEs 101-112 in the network 100 before the PPRinformation 210 is flooded to other NEs 101-112 in the network 100.

The node resource capability 203 indicates various differentcapabilities of, or features supported by, the NE 101-112 sending thenode resource capability 203. In an embodiment, the node resourcecapability 203 indicates whether the NE 101-112 sending the noderesource capability 203 is capable of implementing preferred pathrouting. In an embodiment, the node resource capability 203 indicatesone or more attributes that are supported by sending the node resourcecapability 203. For example, the node resource capability 203 indicateswhether the NE 101-112 sending the node resource capability 203 iscapable of reserving a resource on the PPR 120 according to one or moredifferent attributes. In an embodiment, the node resource capability 203indicates whether the NE 101-112 sending the node resource capability203 is capable of monitoring usage statistics 215 related to theresources reserved for the PPR 120.

In an embodiment, the node resource capability 203 includes one or moreflags indicating whether the NE 101-112 sending the node resourcecapability 203 is capable of implementing preferred path routing. Thenode resource capability 203 also includes one or more flags indicatingeach of the attributes that the NE 101-112 is capable of supporting toreserve a resource on a PPR 120. The node resource capability 203 alsoincludes one or more flags indicating each of the usage statistics thatNE 101-112 is capable of monitoring.

In an embodiment, the node resource capability 203 is a new messagedefined by the preferred path routing protocol. In another embodiment,the node resource capability 203 is a sub Type-Length-Value (TLV) withina body of an IS-IS capable TLV, as further described in IETF RFC 7981,entitled “IS-IS Extension for Advertising Router Information,” by L.Ginsberg, dated October 2016. Additional detail regarding the noderesource capability 203 is further described below with reference toFIGS. 4A-C.

Second, one or more NEs 101-112 within the network 100 may transmitusage statistics 215 to the central entity 175 periodically or throughany other offline mechanism such as gRPC, KAFKA or through streamingtelemetry.

After receiving the PPR information 210 from the central entity 175 orlocally provisioned by the operator at one or more NEs 101-112advertises the PPR information 210 describing PPR 120 to all of theother NEs 101-112 within a respective area 150A-B that the NE 101-112 islocated using the underlying IGP. In an embodiment, the PPR information210 may be included with an advertisement or a PPR-TLV, as described inthe PPR Patent. For example, assuming that NE 103 receives the PPRinformation 210 describing the PPR 120 from the central entity 175 (orotherwise an external entity or operator of the network 100), the NE 103transmits the PPR information 210 to the other NEs 101-102 and 104-107in area 150A of the network 100. Similarly, assuming that NE 110receives the PPR information 210 describing the PPR 120 from the centralentity 175 (or otherwise an external entity or operator of the network100), the NE 103 transmits the PPR information 210 to the other NEs106-109 and 111-112 in area 150B of the network 100.

As shown in FIG. 2 and described above, the PPR information 210 mayinclude information describing the PPR 120, such as, for example, thePPR-ID 230 identifying the PPR 120. The PPR information 210 may alsoinclude one or more PPR-PDEs 245 describing one or more elements on thePPR 120. Each PPR-PDE 245 may include an address, label, or ID of anelement on the PPR 120. The PPR information 210 may also include one ormore attributes 240 associated with a resource to be reserved on the PPR120. As described above, the PPR-ID 230 is a label, address, or ID thatuniquely identifies the PPR 120, and the attributes 240 refer to networkcharacteristics or TE parameters by which a certain resource on the PPR120 is reserved. In an embodiment, the attributes 240 are enforced byone or more elements 101, 124, 104, 125, 105, 126, 106, 135, 112, 134,111, 133, and 110 on the PPR 120 to ensure that the PPR 120 satisfiescertain QoS parameters.

In an embodiment, the attributes 240 specify a bandwidth, a burst size,a per-hop queueing latency, or a lifetime of the PPR 120. For example,the attributes 240 for a PPR 120 may specify a minimum bandwidth or amaximum bandwidth required to transmit a data packet along a link122-135 of the PPR 120. The attributes 240 for a PPR 120 may specify arequired or maximum burst size of a burst transmitted along a link122-126 and 133-135 of the PPR 120. The attributes 240 for a PPR 120 mayspecify a per-hop queuing latency, which indicates a bounded latency foreach NE 101, 104, 105, 106, 112, 111, 110 or hop on the PPR 120. Theattributes 240 may also specify a lifetime of the reservations made forthe PPR 120 such that the reservations are torn down upon expiration ofthe lifetime, unless the NE 101, 104, 105, 106, 112, 111, 110 receives astate refresh of the PPR 120, which will be further described below.Additional details and examples of the attributes 240 are furtherdescribed below with regard to FIGS. 5A-B and 6A-D. Although only thesefour examples of attributes 240 are described herein, it should beappreciated that attributes 240 include any other TE parameter ornetwork characteristic that may be used to provide a certain QoS toclients transmitting and receiving data packets along the PPR 120.

In an embodiment, upon receiving the PPR information 210 from other NEs101-112 in the network 100, the receiving NEs 101-112 are configured toprogram the PPR 120 according to the PPR information 210. Programmingthe PPR 120 according to the PPR information 210 includes updating alocal forwarding database stored at the NE 101-112 to include the PPRinformation 210 in association with a destination address correspondingto the egress NE 110 of the PPR 120 or the destination 180. In anembodiment, the NE 101-112 updates the local forwarding database toinclude the attributes 240 along with the PPR-ID 230 and the PPR-PDEsspecified by the PPR information 210. As described above, in oneembodiment, the local forwarding database is updated only when thePPR-PDEs include the NE 101-112 that received the PPR information 210,and in another embodiment, the local forwarding database is updatedregardless of whether the PPR-PDEs include the NE 101-112 received thePPR information 210.

After updating the local forwarding database based on the received PPRinformation 210, each of the NEs 101-112 transmits (or floods) a nodestatus 220 to the other NEs 101-112 in a respective area 150A-B of thenetwork 100 using the underlying IGP. For example, after updating thelocal forwarding database to include the PPR information 210, the NE 103transmits a node status 220 to NEs 101-102 and 104-107 within area 150A.Similarly, after updating the local forwarding database to include thePPR information 210, the NE 110 transmits a node status 220 to NEs106-109 and 111-112 within area 150B.

A node status 220 indicates whether a resource for the PPR 120 has beensuccessfully reserved according to the attribute 240 included in the PPRinformation 210. In an embodiment, the node status 220 indicates asuccessful reservation of the resource for the PPR 120 when the localforwarding database of the NE 101-112 sending the node status 220 hasbeen successfully updated to include the PPR information 210, includingthe attribute 240. In an embodiment, the node status 220 indicates afailure to reserve one or more resources for the PPR 120 when the localforwarding database of the NE 101-112 sending the node status 220 hasnot been successfully updated to include the PPR information 210,including the attribute 240. Additional details regarding the nodestatus 220 are further described below with regard to FIGS. 7A-D.

After updating the local forwarding database and sending the node status220, data packets may be forwarded along the PPR 120 in the data plane.As further described in the PPR Patent, only data packets that includethe PPR-ID 230 are forwarded along the PPR 120. For example, assuming NE101 receives a data packet with a PPR-ID 230 in a header of the datapacket, the NE 101 performs a lookup at the local forwarding databaseusing the PPR-ID 230 to determine a next hop (e.g., next element 101,124, 104, 125, 105, 126, 106, 135, 112, 134, 111, 133, and 110 or nextsegment). In an embodiment, the forwarding database includes entriescorresponding to destination addresses and PPR-IDs 230 indicating thenext hop or element toward which to forward a data packet. The lookupmay be performed at the local database by searching the forwardingdatabase for the entry corresponding to the destination address andPPR-ID 230 included in the data packet. The data packet is thenforwarded toward the next hop based on the PPR-PDEs stored inassociation with the PPR-ID 230 in the entry of the forwarding database.

In an embodiment, the NE 101 is also configured to perform the lookup atthe local forwarding database to determine an attribute 240 associatedwith a resource reserved for this PPR 120 and then determines whetherthe path to the next hop on the PPR 120 satisfies the attribute 240.When the determined next hop on the PPR 120 satisfies the attribute 240,the NE 101 forwards to the data packet to the next hop on the PPR 120(e.g., along link 124 to NE 104). In this manner, each of the NEs 101,104, 105, 106, 112, and 111 on the PPR 120 to the egress NE 110determines whether a next hop on the PPR 120 satisfies the attribute 240and forwards the data packet to the next hop only when the next hopsatisfies the attribute 240.

As data packets continue to be forwarded on the PPR 120 in the dataplane, each of the NEs 101, 104, 105, 106, 112, 111, and 110 on the PPR120 monitor and collect usage statistics 215 of network resources alongthe PPR 120. In an embodiment, usage statistics 215 refer to statisticsregarding the usage of various resources along the PPR 120. In anembodiment, each of the NEs 101, 104, 105, 106, 112, 111, and 110 may bepre-configured by, for example, the operator of the network 100 or thecentral entity 175 to monitor usage statistics 215 of network resourcesalong the PPR 120 or other paths along which the NEs 101, 104, 105, 106,112, 110, and 110 transmit data.

After collecting the usage statistics 215, one or more of the NEs101-112 may transmit the usage statistics 215 to the central entity 175periodically or through any other offline mechanism such as gRPC, KAFKAor other streaming telemetry tools.

For example, assuming NE 104 collects usage statistics 215, such as theutilized bandwidth at link 126 along the PPR 120, the NE 104 maytransmit this usage statistic 215 to the other NEs 101-103 and 105-107in the area 150A using the underlying IGP. In an embodiment, the NE101-112 within the network 100 that is configured to perform northboundcommunication with the central entity 175 to transmit control data tothe central entity 175 transmits the usage statistics 215 to the centralentity 175. For example, assume that the NE 103 is configured as theBorder Gateway Protocol (BGP) Link State (BGP-LS) speaker enabled withBGP to perform northbound communication with the central entity 175. Inthis case, NE 103 transmits the usage statistics 215 to the centralentity 175 using BGP-LS after having received the usage statistics 215from NE 104. In another embodiment, the central entity 175 may requestand receive usage statistics 215 directly from any of the NEs 101, 104,105, 106, 112, 111, and 110 on the path using, for example, protocolssuch as g-Remote Procedure Calls (gRPC) or KAFKA.

In an embodiment, usage statistics 215 include data regarding the amountof used or unused resources on the PPR 120. The usage statistics 215 mayinclude a per-PPR queuing delay occurring at an NE 101, 104, 105, 106,112, 111, or 110 on a PPR 120 and a PPR bandwidth describing a utilizedbandwidth on a link 124-126 and 133-135 attached to an NE 101, 104, 105,106, 112, 111, or 110 on a PPR 120. The PPR bandwidth may also describebandwidth violations occurring on a link 124-126 and 133-135 attached toan NE 101, 104, 105, 106, 112, 111, or 110 on a PPR 120. Additionaldetails and examples of the usage statistics 215 are further describedbelow with regard to FIGS. 8A-C. Although only these two examples ofusage statistics 215 are described herein, it should be appreciated thatusage statistics 215 includes any other measurement of utilized orunutilized network resources on a PPR 120.

FIG. 3 is a diagram of an embodiment of an NE 300 in a network such asthe network 100. NE 300 may be implemented as the central entity 175 orthe NEs 101-112. The NE 300 may be configured to implement and/orsupport the routing mechanisms described herein. The NE 300 may beimplemented in a single node or the functionality of NE 300 may beimplemented in a plurality of nodes. One skilled in the art willrecognize that the term NE encompasses a broad range of devices of whichNE 300 is merely an example. While NE 300 is described as a physicaldevice, such as a router or gateway, the NE 300 may also be a virtualdevice implemented as a router or gateway running on a server or ageneric routing hardware (whitebox).

The NE 300 is included for purposes of clarity of discussion, but is inno way meant to limit the application of the present disclosure to aparticular NE embodiment or class of NE embodiments. At least some ofthe features and/or methods described in the disclosure may beimplemented in a network apparatus or module such as a NE 300. Forinstance, the features and/or methods in the disclosure may beimplemented using hardware, firmware, and/or software installed to runon hardware. As shown in FIG. 3, the NE 300 comprises one or moreingress ports 310 and a receiver unit (Rx) 320 for receiving data, atleast one processor, logic unit, or central processing unit (CPU) 330 toprocess the data, transmitter unit (Tx) 340 and one or more egress ports350 for transmitting the data, and a memory 360 for storing the data.

The processor 330 may comprise one or more multi-core processors and becoupled to a memory 360, which may function as data stores, buffers,etc. The processor 330 may be implemented as a general processor or maybe part of one or more application specific integrated circuits (ASICs)and/or digital signal processors (DSPs). The processor 330 may comprisea network configuration module 335, which may perform processingfunctions of the central entity 175 or the NEs 101-112. The networkconfiguration module 335 may also be configured to perform the steps ofmethod 900, and/or any other method discussed herein. As such, theinclusion of the network configuration module 335 and associated methodsand systems provide improvements to the functionality of the NE 300.Further, the network configuration module 335 effects a transformationof a particular article (e.g., the network) to a different state. In analternative embodiment, network configuration module 335 may beimplemented as instructions stored in the memory 360, which may beexecuted by the processor 330.

The memory 360 may comprise a cache for temporarily storing content,e.g., a random-access memory (RAM). Additionally, the memory 360 maycomprise a long-term storage for storing content relatively longer,e.g., a read-only memory (ROM). For instance, the cache and thelong-term storage may include dynamic RAMs (DRAMs), solid-state drives(SSDs), hard disks, or combinations thereof. The memory 360 may beconfigured to store the PPR information 210, which includes PPR-IDs 230,attributes 240, and the PPR-PDEs 245. In addition, the memory 360 isconfigured to store the node resource capability 203, usage statistics215, a forwarding database 343, and a link state database 351. In anembodiment, the forwarding database 343 stores entries describingforwarding rules for how a particular NE 300 (e.g., NE 101-112 of FIGS.1-2) should forward a data packet that includes a PPR-ID 230 and/or adestination address.

It is understood that by programming and/or loading executableinstructions onto the NE 300, at least one of the processor 330 and/ormemory 360 are changed, transforming the NE 300 in part into aparticular machine or apparatus, e.g., a multi-core forwardingarchitecture, having the novel functionality taught by the presentdisclosure. It is fundamental to the electrical engineering and softwareengineering arts that functionality that can be implemented by loadingexecutable software into a computer can be converted to a hardwareimplementation by well-known design rules. Decisions betweenimplementing a concept in software versus hardware typically hinge onconsiderations of stability of the design and numbers of units to beproduced rather than any issues involved in translating from thesoftware domain to the hardware domain. Generally, a design that isstill subject to frequent change may be preferred to be implemented insoftware, because re-spinning a hardware implementation is moreexpensive than re-spinning a software design. Generally, a design thatis stable that will be produced in large volume may be preferred to beimplemented in hardware, for example in an ASIC, because for largeproduction runs the hardware implementation may be less expensive thanthe software implementation. Often a design may be developed and testedin a software form and later transformed, by well-known design rules, toan equivalent hardware implementation in an ASIC that hardwires theinstructions of the software. In the same manner as a machine controlledby a new ASIC in a particular machine or apparatus, likewise a computerthat has been programmed and/or loaded with executable instructions maybe viewed as a particular machine or apparatus. In some embodiments, theNE 300 may be configured to implement OSPFv2, OSPFv3, IS-IS, or directSDN controller based on network implementations.

FIGS. 4A-C are diagrams illustrating examples of a node resourcecapability 203 sent by an NE 101-112 in the network 100, and fieldswithin the node resource capability 203, according to variousembodiments of the disclosure. In particular, FIG. 4A is a diagramillustrating an example of a node resource capability 203 sent by an NE101-112 to every other NE 101-112 in the area 150A-B or the network 100and the central entity 175 according to various embodiments of thedisclosure. As described above, the node resource capability 203indicates various different capabilities of the NE 101-112 sending thenode resource capability 203.

As shown in FIG. 4A, the node resource capability 203 includes a node ID403 identifying the NE 101-112 sending the node resource capability 203.The node ID 403 may be a label, address, or ID that uniquely identifiesthe NE 101-112 sending the node resource capability 203.

The node resource capability 203 also includes resource reservationcapabilities 406. The resource reservation capabilities 406 may includeone or more flags indicating whether the NE 101-112 sending the noderesource capability 203 is capable of reserving a resource on the PPR120 according to an attribute 240. In an embodiment, the resourcereservation capabilities 406 includes a flag indicating whetherreserving a minimum or maximum bandwidth on a link 122-135 attached theNE 101-112 sending the node resource capability 203 is supported by theNE 101-112. In an embodiment, the resource reservation capabilities 406includes a flag indicating whether setting a burst size or maximum burstsize permitted to be transmitted on a link 122-135 attached the NE101-112 sending the node resource capability 203 is supported by the NE101-112. In an embodiment, the resource reservation capabilities 406includes a flag indicating whether enforcing a per hop maximum queuinglatency at the NE 101-112 sending the node resource capability 203 issupported by the NE 101-112. In an embodiment, the resource reservationcapabilities 406 includes a flag which indicates whether setting andenforcing a lifetime or expiration timer for the PPR 120 is supported bythe NE 101-112.

FIG. 4B shows an example a node resource capability 450 defined within abody of the IS-IS Router Capability TLV, as defined by RFC 7981,according to various embodiments of the disclosure. The node resourcecapability 450 also defines all the TE parameters that are supported bythe NE 101-112 sending the node resource capability 450.

As shown by FIG. 4B, the node resource capability 450 includes a typefield 453, a length field 456, and reservation capability (RC) flagsfield 459. The type field 453 may include a value assigned by theInternet Assigned Numbers Authority (IANA) from the IS-IS RouterCapability TLV Registry. The value carried in the type field 453indicates that the node resource capability 450 includes RC flags 459related to resource reservation capabilities 406 on a PPR 120. Thelength field 456 includes a value indicating a total length of the noderesource capability 450 in bytes. The RC flags field 459 is a 2 octetfield including multiple flags, as represented in the reservationcapability sub-TLV shown in FIG. 4C.

FIG. 4C shows an example of a reservation capability sub-TLV 470 that isincluded in the RC flags field 459 according to various embodiments ofthe disclosure. The RC flags field 459 may include four flags or bits: aB flag 473, a S flag 476, a L flag 479, a T flag 481, reserved bits 484,and an E flag 487.

The B flag 473, also referred to as Bit-0 or the B Bit, is set toindicate that minimum or maximum bandwidth reservation is supported bythe NE 101-112 sending the node resource capability 450. The S flag 476,also referred to as Bit-1 or the S Bit, is set to indicate that burstsize handling is supported by the NE 101-112 sending the node resourcecapability 450. The L flag 479, also referred to as Bit-2 or the L Bit,is set to indicate that per-hop maximum queuing is supported by the NE101-112 sending the node resource capability 450. The T flag 481, alsoreferred to as Bit-3 or the T Bit, is set to indicate that a lifetime,or expiration timer for the PPR 120 is supported by the NE 101-112sending the node resource capability 450. The reserved bits 484 areempty and reserved for future use. The E flag 484, also referred to asBit-15 or the E Bit, is set to indicate that one more 16-bit statusfield follows the E flag 484.

FIGS. 5A-B are diagrams illustrating an example of an advertisement 500sent by an NE 101-112 in the network 100, and attributes 240 included inthe advertisement 500, according to various embodiments of thedisclosure. In particular, FIG. 5A is a diagram illustrating an exampleof an advertisement 500 including PPR information 210 according tovarious embodiments of the disclosure. As described above, the PPRinformation 210 describing the PPR 120 is received by a headend NE101-112 by either the central entity 175 or an external entity, such asan operator of network 100. After receiving the PPR information 210, theheadend NE 101-112 floods the advertisement 500 including the PPRinformation 210 through the entire respective area 150A—using anunderlying IGP of the respective area 150A-B. Flooding the advertisement500 throughout the respective area 150A-B refers to transmitting theadvertisement 500 to every other NE 101-112 in the respective area150A-B. The NE 101-112 may also flood the advertisement 500 through theentire domain (e.g., network 100) at which the headend NE 101-112 islocated using an underlying IGP of the network 100. Flooding theadvertisement 500 throughout the network 100 refers to transmitting theadvertisement 500 to every other NE 101-112 in the network 100.

As shown in FIG. 5A, the PPR information 210 includes the PPR-ID 230, aPPR type 503, one or more PPR-PDEs 245A-N, and one or more attributes240A-N. As described above, the PPR-ID 230 is a label, address, oridentifier that uniquely identifies the PPR 120. The PPR-ID 230 may beencoded in many different ways, such as, for example, as an IPv4address, IPv6 address, or MPLS label.

The PPR type 503 defines the kind or type of the labels, addresses, orIDs of the PPR-ID 230 and/or the elements 101-112 and 122-135 (NEs101-112 and links 122-135) on the PPR 120, which are encoded in thePPR-PDEs 245A-N. As described above, each of the PPR-PDEs 245A-Nincludes a label, address, or ID identifying an element 101-112 and122-135 on the PPR 120. For example, each of the elements 101-112 and122-135 on the PPR 120 may be encoded as an MPLS label, an IPv4 address,an IPv6 address, etc. The PPR type 503 defines an encoding scheme usedby the PPR-ID 230 and/or each of the PPR-PDEs 425A-N.

As described above, the attributes 240A-N describe one or more networkcharacteristics or TE parameters that should be applied to at least oneresource on the PPR 120. Various examples of the attributes 240A-N aredescribed below with reference to FIG. 5B. While FIG. 5A only shows thePPR information 210 including the PPR-ID 230, the PPR type 503, one ormore PPR-PDEs 245A-N, and one or more attributes 240A-N, the PPRinformation 210 may include other information as described in the PPRPatent.

FIG. 5B is a diagram illustrating examples of the attributes 240A-Ncarried in the PPR information 210 describing a PPR 120 according tovarious embodiments of the disclosure. As shown in FIG. 5B, theattributes 240A-N include a bandwidth sub-TLV 553, a burst size sub-TLV556, a per-hop queuing sub-TLV 559, and a lifetime sub-TLV 561. Whileonly these four attributes 240A-N are shown and described with referenceto FIG. 5B, it should be appreciated that attributes 240A-N may includeany other attribute defining a TE parameter or a network characteristicfor a PPR 120.

The bandwidth sub-TLV 553 may be encoded to carry information regardingbandwidth requirement 543, such as a minimum bandwidth or a maximumbandwidth required to transmit a data packet along a link 124-126 and133-135 of the PPR 120. For example, the bandwidth sub-TLV 553 mayinclude a bandwidth requirement 543 defining a minimum bandwidthrequired on a link 124-126 and 133-135 of the PPR 120 to permittransmitting a data packet including a PPR-ID 230 corresponding to thePPR 120 along the link 124-126 and 133-135. Similarly, the bandwidthsub-TLV 553 may include a bandwidth requirement 543 defining a maximumbandwidth allowed on a link 124-126 and 133-135 of the PPR 120 to permittransmitting a data packet including a PPR-ID 230 corresponding to thePPR 120 along the link 124-126 and 133-135. An example of the bandwidthsub-TLV 553 is shown and described below with reference to FIG. 6A.

The burst size sub-TLV 556 may be encoded to carry a burst size 546,such as a maximum burst size of a burst transmitted along a link 124-126and 133-135 of the PPR 120. For example, the burst size sub-TLV 556 mayinclude burst size 546 defining a maximum burst size of a burst of datapackets including the PPR-ID 230 permitted to be transmitted on a link124-126 and 133-135 of the PPR 120. Similarly, the burst size sub-TLV556 may include a burst size 546 defining minimum burst size of a burstof data packets including the PPR-ID 230 permitted to be transmitted ona link 124-126 and 133-135 of the PPR 120. An example of the burst sizesub-TLV 556 is shown and described below with reference to FIG. 6B.

The per-hop queuing size sub-TLV 559 may be encoded to carry a boundedlatency 549 for each element (e.g., NE 101, link 124, NE 104, link 125,NE 105, link 126, NE 106, link 135, NE 112, link 134, NE 111, link 133,and NE 110) or hop on the PPR 120. For example, the per-hop queuing sizesub-TLV 559 may include a maximum bounded latency 549 permitted on eachNE 101, 104, 105, 106, 112, 111, 110 on the PPR 120 such that datapackets including the PPR-ID 230 for the PPR 120 may only be transmittedto NEs 101, 104, 105, 106, 112, 111, 110 with a bounded latency lessthan the maximum bounded latency 549. An example of the per-hop queuingsize sub-TLV 559 is shown and described below with reference to FIG. 6C.

The lifetime sub-TLV 561 may be encoded to carry a lifetime 551 of thereservations made for the PPR 120 such that the reservations are teareddown upon expiration of the lifetime 551. In an embodiment, tearing downthe reservations refers to removing the PPR information 210 from theforwarding database 343 and/or removing the reservation of the resourcealong an element 101, 124, 104, 125, 105, 126, 106, 135, 112, 134, 111,133, and 110.

The lifetime 551 may be indicated in the time unit of seconds. Forexample, the lifetime sub-TLV 561 may include a lifetime 551, or amaximum amount of time, that a resource is reserved for a PPR 120. Forexample, when an NE 101-112 receives an advertisement 500 with the PPRinformation 210 including a lifetime 551 for the PPR 120, the forwardingdatabase 343 is updated to indicate the lifetime 551, and a soft timeris initiated and expected to expire at the time period indicated by thelifetime 551.

The lifetime 551 may be extended when a state refresh is received by theNE 101-112 from which the original PPR information 210 was received. Inan embodiment, a state refresh is another advertisement 500 containingthe same PPR information 210 for the PPR information 210. In anembodiment, when a state refresh is received from an originating headendNE 101-112 before the expiration of the soft timer, the lifetime 551 isreset and initiated again. If a state refresh is not received before theexpiration of the soft timer, then the resources reserved for the PPR120 are teared down and the forwarding database 343 is updated toreflect the tearing down of the PPR 120. An example of the lifetimesub-TLV 561 is shown and described below with reference to FIG. 6D.

FIGS. 6A-D show examples of the attributes 240A-N described in FIG. 5Baccording to various embodiments of the disclosure. FIG. 6A shows anexample of the bandwidth sub-TLV 553, FIG. 6B shows an example of aburst size sub-TLV 556, FIG. 6C shows an example of a per-hop queuingsub-TLV 559, and FIG. 6D shows an example of a lifetime sub-TLV 561. Inan embodiment, the sub-TLVs for the various attributes 240A-N describedin FIGS. 6A-D may be included in the IS-IS PPR Attribute Sub-TLVdescribed in the PPR Patent. In an embodiment, the sub-TLVs for thevarious attributes 240A-N described in FIGS. 6A-D may be included in theOSPFv2 or OSPFv3 PPR Attribute Sub-TLV described in the PPR Patent. Inanother embodiment, the sub-TLVs for the various attributes 240A-Ndescribed in FIGS. 6A-D may be entirely new messages, or may be includedin any other protocol by which NEs 101-112 transmit data.

Referring first to FIG. 6A, shown is an example of a bandwidth sub-TLV553 including a type field 603, a length field 606, reserved bits 609, aminimum bandwidth 611, and a maximum bandwidth 614. The type field 603includes a value indicating that the bandwidth sub-TLV 553 includesbandwidth related information (e.g., bandwidth requirement 543)associated with a resource to be reserved on the PPR 120. The valuecarried in the bandwidth sub-TLV 553 may be assigned by the IANA. Thelength field 606 is 10 octets and defines a length of the bandwidthsub-TLV 553. The reserved bits 609 are empty and reserved for futureuse.

The minimum bandwidth field 611 carries a bandwidth requirement 543defining a minimum bandwidth (also referred to as committed informationrate (CIR)) that is required on a link 124-126 and 133-135 attached toan NE 101, 104, 105, 106, 112, 111, and 110 on the PPR 120 for datapackets (comprising the PPR-ID 230 of the PPR 120) to be transmittedover the link 124-126 and 133-135 on the PPR 120. The maximum bandwidthfield 614 carries a bandwidth requirement 543 defining maximum bandwidth(also referred to as peak information rate (PIR)) that is required on alink 124-126 and 133-135 attached to an NE 101, 104, 105, 106, 112, 111,and 110 on the PPR 120 for data packets (comprising the PPR-ID 230 ofthe PPR 120) to be transmitted over the link 124-126 and 133-135 on thePPR 120. The minimum bandwidth and/or maximum bandwidth may be indicatedin the minimum bandwidth field 611 and/or maximum bandwidth field 614,respectively, using the unit of megabits per second (Mbps). Although thebandwidth sub-TLV 553 includes fields 611 and 614 for both a minimum andmaximum bandwidth, it should be appreciated that the bandwidth sub-TLV553 may define only a minimum bandwidth, only a maximum bandwidth, orboth a minimum and maximum bandwidth.

Referring next to FIG. 6B, shown is an example of a burst size sub-TLV556 including a type field 633, a length field 636, reserved bits 639,and a burst size field 641. The type field 633 includes a valueindicating that the burst size sub-TLV 556 includes burst size relatedinformation (e.g., burst size 546) associated with a resource to bereserved on the PPR 120. The value carried in the type field 633 may beassigned by the IANA. The length field 636 is 6 octets and defines alength of the burst size sub-TLV 556. The reserved bits 639 are emptyand reserved for future use.

The burst size field 641 carries a burst size 546, which may definemaximum burst size of a burst carried on a link 122-135 of the PPR 120.A burst refers to an aggregation of data packets including the PPR-ID230 of PPR 120. The burst size 546 may be indicated in the burst sizefield 641 using the unit of 1000 (K) bytes.

Referring next to FIG. 6C, shown is an example of a per-hop queuinglatency size sub-TLV 559 including a type field 653, a length field 656,reserved bits 659, a T flag 661, a flags field 664, and a latency field667. The type field 653 includes a value indicating that the per-hopqueuing latency size sub-TLV 559 includes per-hop queuing latencyinformation (e.g., bounded latency 549) associated with an NE 101-112 onthe PPR 120. The value carried in the type field 653 may be assigned bythe IANA. The length field 656 is 6 octets and defines a length of theper-hop queuing latency size sub-TLV 559. The reserved bits 659 areempty and reserved for future use.

The T flag 661, also referred to as the T bit, is set to 0 if a boundedlatency 549 carried in the latency field 667 is expressed inmilliseconds. The T flag 661 is set to 1 if a bounded latency 549carried in the latency field 667 is expressed in microseconds. The flagsfield 664 is one octet and includes one or more flags related to thebounded latency 549 carried the latency field 667. The latency field 667carries a bounded latency 549 defined as an expected maximum queuinglatency for each NE 101-112 on the PPR 120. In an embodiment, datapackets (including the PPR-ID 230 of the PPR 120) may only betransmitted to or received by an NE 101, 104, 105, 106, 112, 111, and110 on the PPR 120 if a queuing latency at that NE 101, 104, 105, 106,112, 111, and 110 is less than the maximum queuing latency carried bythe latency field 667. In an embodiment, when an attribute 240A-Ncarries an expected maximum queuing latency, a minimum bandwidth shouldalso be carried in the attributes 240A-N.

Referring next to FIG. 6D, shown is an example of a lifetime sub-TLV 561including a type field 670, a length field 673, reserved bits 676, aflags field 679, and a lifetime field 681. The type field 670 includes avalue indicating that the lifetime sub-TLV 561 includes lifetime relatedinformation (e.g., lifetime 551) associated with the PPR 120. The valuecarried in the type field 670 may be assigned by the IANA. The lengthfield 673 is 6 octets and defines a length of the lifetime sub-TLV 561.The flags field 679 is one octet and carries data associated with thelifetime 551 included in the lifetime field 681. The lifetime field 681includes the lifetime 551, or the time period during which resources arereserved along a PPR 120, which can only be reset upon receiving a staterefresh (another advertisement 500 with the same PPR information 210).The reserved bits 676 are empty and reserved for future use.

Therefore, FIGS. 5A-B and 6A-D describe the attributes 240A-N that areincluded in the PPR information 210 advertised for a PPR 120 anddifferent ways to encode the attributes 240A-N into the advertisement500. In an embodiment, the attributes 240A-N may be modified or updatedby sending another advertisement 500 including modified attributes240A-N in the PPR information 210. For example, the NE 101-112 thatoriginally sent the advertisement 500 including the PPR information 210may receive modified attributes 240A-N for the PPR 120 (from either anoperator of the network 100 or a central entity 175). In this case, theNE 101-112 may send another advertisement 500 with the same PPRinformation 210, except including the modified attributes 240A-N insteadof the originally sent attributes 240A-N. The receiving NEs 101-112 thatreceive the modified attributes 240A-N may update the locally storedforwarding database 343 to reflect the received modified attributes240A-N.

FIGS. 7A-D are diagrams illustrating an example of a node status 220,and fields within the node status 200, sent by NEs 101, 104, 105, 106,112, 111, and 110 on the PPR 120 to every other NE 101-112 in the area150A-B or the network 100 and the central entity 175 according tovarious embodiments of the disclosure. As described above, a node status220 is a message indicating whether a resource for the PPR 120 has beensuccessfully reserved according to the attribute 240A-N included in thePPR information 210.

As shown in FIG. 7A, the node status 220 includes a node ID 403identifying the NE 101, 104, 105, 106, 112, 111, and 110 sending thenode status 220. The node ID 403 may be a label, address, or ID thatuniquely identifies the NE 101, 104, 105, 106, 112, 111, and 110 sendingthe node status 220.

The node status 220 also includes a resource reservation status 706. Theresource reservation status 706 may include one or sub-TLVs and one ormore flags indicating a status of certain resources that have beenreserved according to an attribute 240A-N (also referred to herein as“attribute 240”) specified for the PPR 120. An example of a sub-TLV thatmay be included in the resource reservation status 706 is shown anddescribed below with reference to FIGS. 7B-C. Examples of flags that maybe included in the resource reservation status 706 is shown anddescribed below with reference to FIG. 7D.

FIG. 7B shows an example of a node status TLV 725 that may be includedin the resource reservation status 706 according to various embodimentsof the disclosure. In an embodiment, the node status TLV 725 may be anew top level IS-IS TLV, OSPFv2 TLV, or OSPFv3 TLV defined to indicatethe status of PPR TE resource reservation by each NE 101, 104, 105, 106,112, 111, and 110 on the PPR 120. In this embodiment, the node statusTLV 725 is generated by an NE 101, 104, 105, 106, 112, 111, and 110 onthe PPR 120 which performs the reservation of resources. In anotherembodiment, the node status TLV 725 is an entirely new message, or canbe encoded into another protocol by which NEs 101, 104, 105, 106, 112,111, and 110 are configured to transmit data.

The node status TLV 725 includes a type field 727, a length field 730,reserved bits 733, and one or more sub-TLVs 740. The type field 727carries a value assigned by the IANA indicating that the node status TLV725 includes data regarding a status of resources reserved for a PPR120. For example, the value may be assigned from the IS-IS top level TLVregistry. The length field 730 includes a value indicating a totallength of the node status TLV 725 in bytes. The sub-TLVs 740 are furtherdescribed below with reference to FIG. 7C. The reserved bits 733 areempty and reserved for future use.

Referring next to FIG. 7C, shown is an example of a sub-TLV 740 includedin a node status 220 according to various embodiments of the disclosure.As shown by FIG. 7C, the sub-TLV 740 includes a type field 743, a lengthfield 746, a PPR-ID type field 749, a PPR-ID length field 751 (shown asPPR-ID Len in FIG. 7C), a PPR-ID value field 753, and a 16-bit statusbit-field 756. The type field 743 carries a value assigned by the IANAindicating that the sub-TLV 740 includes data regarding a status ofresources reserved for a PPR 120. The length field 746 includes a valueindicating a total length of the sub-TLV 740 in bytes. The PPR-ID typefield 749 carries a value indicating a type of PPR-ID 230 carried in thePPR-ID value field 753 (e.g., whether the PPR-ID 230 is an MPLS label,an IPV4 address, an IPv6 address, etc.). The PPR-ID length field 751carries a length of the PPR-ID value field 753. The PPR-ID value field753 carries the PPR-ID 230 identifying the PPR 120. The 16-bit statusbit-field 756 includes various flags describing the status of resourcesreserved on the PPR 120 and is further described below with reference toFIG. 7D.

Referring next to FIG. 7D, shown is an example of a 16-bit statusbit-field 756 included in a node status TLV 725 of a node status 220according to various embodiments of the disclosure. The 16-bit statusbit-field 756 includes a B flag 759, an S flag 761, an L flag 764, a Tflag 767, reserved bits 770, and an E flag 773.

The B flag 759, also referred to as Bit-0 or the B Bit, indicateswhether bandwidth requirement 543 (defined as either the minimum ormaximum bandwidth reservation for a resource on the PPR 120) has beenreserved by the NE 101, 104, 105, 106, 112, 111, or 110 sending the nodestatus 220. The S flag 761, also referred to as Bit-1 or the S Bit, isset to indicate whether the burst size 546 handling on the PPR 120 hasbeen set by the NE 101, 104, 105, 106, 112, 111, or 110 sending the nodestatus 220. The L flag 764, also referred to as Bit-2 or the L Bit, isset to indicate whether a bounded latency 549 defined as a per-hopmaximum queuing for the PPR 120 has been set by the NE 101, 104, 105,106, 112, 111, or 110 sending the node status 220. The T flag 767, alsoreferred to as Bit-3 or the T Bit, is set to indicate whether a lifetime551 or expiration timer for the PPR 120 has been set by the NE 101, 104,105, 106, 112, 111, or 110 sending the node status 220. The reservedbits 770 are empty and reserved for future use. The E flag 773, alsoreferred to as Bit-15 or the E Bit, is set to indicate that one more 16bit status field(s) follows the E flag 773.

In an embodiment, one of the NEs 101, 104, 105, 106, 112, 111, or 110 onthe PPR 120 may identify that one of the elements 101, 124, 104, 125,105, 126, 106, 135, 112, 134, 111, 133, or 110 on the PPR 120 isunavailable or failed. In this case, an NE 101, 104, 105, 106, 112, 111,or 110 adjacent to or attached to the unavailable element 101, 124, 104,125, 105, 126, 106, 135, 112, 134, 111, 133, or 110 may notify theheadend NE 101-112 that sent the original advertisement 500 of theunavailable element 101, 124, 104, 125, 105, 126, 106, 135, 112, 134,111, 133, or 110. The NE 101-112 adjacent to or attached to theunavailable element 101, 104, 105, 106, 112, 111, or 110 may notify theNE 101-112 in the network 100 acting as the BGP-LS speaker, such thatthe BGP-LS speaker notifies the central entity 175 of the unavailableelement 101, 124, 104, 125, 105, 126, 106, 135, 112, 134, 111, 133, or110. In an embodiment, the central entity 175, which stores the networktopology of network 100, determines another PPR 120 without theunavailable element 101, 124, 104, 125, 105, 126, 106, 135, 112, 134,111, 133, or 110 satisfies the same attributes 240A-N as the originalPPR 120, and transmits PPR information 210 related to the newlydetermined PPR 120 to a headend NE 101-112. The headend NE 101-112 againfloods the area 150A-B or the network 100 with the PPR information 210describing the newly determined PPR 120.

FIGS. 8A-C are diagrams illustrating an example of usage statistics 215collected by NEs 101, 104, 105, 106, 112, 111, and 110 on the PPR 120,and fields within the usage statistics 215, according to variousembodiments of the disclosure. As described above, usage statistics 215refers to statistics regarding the usage of various resources along thePPR 120. In an embodiment, the usage statistics 215 may be floodedthrough the respective area 150A-B or network 100 until the usagestatistics 215 reaches a BGP-LS speaker within the respective area150A-B or network 100. The BGP-LS speaker then transmits the usagestatistics 215 to the central entity 175, such that the central entity175 may modify the PPR 120 if necessary. In another embodiment, the NE101-112 may directly send the usage statistics 215 to the central entity175, such that the central entity 175 may modify the PPR 120 ifnecessary.

As shown in FIG. 8A, the usage statistics 215 may include a node ID 403identifying the NE 101, 104, 105, 106, 112, 111, and 110 on the PPR 120sending the usage statistics 215. The node ID 403 may be a label,address, or ID that uniquely identifies the NE 101, 104, 105, 106, 112,111, or 110 sending the usage statistics 215. The usage statistics 215also includes a PPR-ID 230 identifying the PPR 120 being monitored anddescribed by the usage statistics 215.

The usage statistics 215 also includes collected network usagestatistics 803, which may include a queue delay 806 and a bandwidthstatistics 809. The queue delay 806 indicates a queuing or transmissiondelay occurring at an NE 101, 104, 105, 106, 112, 111, and 110 on thePPR 120. The bandwidth statistics 809 includes bandwidth relatedstatistics of the PPR 120, such as utilized bandwidth along a link124-126 and 133-135 of the PPR 120, unutilized bandwidth along a link124-126 and 133-135 of the PPR 120, or a bandwidth violation along alink 124-126 and 133-135 of the PPR 120. A bandwidth violation can occurbecause of local failures or due to resource exhaustion set aside for aPPR 120. Examples of TLVs or sub-TLVs carrying collected network usagestatistics 803 included in the usage statistics 215 is shown anddescribed below with reference to FIGS. 8B-C.

Referring next to FIG. 8B, shown is an example of a per-PPR queueingdelay sub-TLV 850 that may be included in the usage statistics 215according to various embodiments of the disclosure. In an embodiment,the per-PPR queueing delay sub-TLV 850 may be a new sub-TLV included inthe IETF RFC 7810, entitled “IS-IS Traffic Engineering (TE) MetricExtensions,” by S. Previdi, et. al., dated May 2016. In an embodiment,the per-PPR queueing delay sub-TLV 850 may be a new message for anexisting protocol or a new protocol.

The per-PPR queueing delay sub-TLV 850 includes a type field 853, alength field 856, reserved bits 859, an average queue delay variationfield 861, a PPR-ID type field 864, a PPR-ID length field 867 (shown asPPR-ID Len in FIG. 8B), and a PPR-ID value field 869. The type field 853carries a value assigned by the IANA indicating that the per-PPRqueueing delay sub-TLV 850 includes data regarding the queue delay 806occurring at NEs 101, 104, 105, 106, 112, 111, or 110 along a PPR 120.The length field 856 includes a value indicating a total length of theper-PPR queueing delay sub-TLV 850 in bytes. The reserved bits 859 areset to 0 and reserved for future use.

The average queue delay variation field 861 is a 24 bit field thatcarries the queue delay 806, which is an average PPR queue delayvariation over a configurable interval in microseconds. The average PPRqueue delay variation is encoded into the average queue delay variationfield 861 as an integer value. When the average queue delay variation isset to 0 in the average queue delay variation field 861, the NE 101,104, 105, 106, 112, 111, or 110 sending the usage statistics 215 has notmeasured the average queue delay variation. The PPR-ID type field 864,the PPR-ID length field 867, and the PPR-ID value field 869 are similarto the PPR-ID type field 749, the PPR-ID length field 751, and thePPR-ID value field 753, respectively.

Referring next to FIG. 8C, shown is an example of a unidirectionalutilized PPR bandwidth sub-TLV 870 that may be included in the usagestatistics 215 according to various embodiments of the disclosure. In anembodiment, the unidirectional utilized PPR bandwidth sub-TLV 870 may bea new sub-TLV included in the IETF RFC 7810, entitled “IS-IS TrafficEngineering (TE) Metric Extensions,” by S. Previdi, et. al., dated May2016. In an embodiment, the unidirectional utilized PPR bandwidthsub-TLV 870 may be a new message for an existing protocol or a newprotocol.

The unidirectional utilized PPR bandwidth sub-TLV 870 includes a typefield 873, a length field 876, a utilized bandwidth field 879, a PPR-IDtype field 881, a PPR-ID length field 882 (shown as PPR-ID Len in FIG.8C), and a PPR-ID value field 883. The type field 873 carries a valueassigned by the IANA indicating that the unidirectional utilized PPRbandwidth sub-TLV 870 includes bandwidth statistics 809 regarding autilized bandwidth of a link 124-126 and 133-135 reserved along a PPR120. The length field 876 includes a value indicating a total length ofthe unidirectional utilized PPR bandwidth sub-TLV 870 in bytes.

The utilized bandwidth field 879 is a field that carries the bandwidthstatistic 809, which may be bandwidth utilization per PPR 120 (or perPPR-ID 230) on a link 124-126 and 133-135 along a PPR 120, forwardingadjacency, or bundled link floating-point format with units of bytes persecond. The PPR-ID type field 881, the PPR-ID length field 882, and thePPR-ID value field 883 are similar to the PPR-ID type field 749, thePPR-ID length field 751, and the PPR-ID value field 753, respectively.

FIG. 9 is a method 900 for implementing resource reservation andmaintenance on a PPR 120 according various embodiments of thedisclosure. In an embodiment, method 900 may be performed by a headendor ingress NE 101-112 in a network 100. In an embodiment, method 900 maybe performed after a central entity 175 obtains and transmits PPRinformation 210 to an NE 101-112 in the network 100.

At step 903, an advertisement 500 comprising PPR information 210describing a path from a source to a destination is received. Forexample, Rx 320 receives the PPR information 210 from the central entity175 or another NE 101-112. The PPR information 210 includes a PPR-ID 230and an attribute 240 associated with a resource to be reserved on thePPR 120. In an embodiment, the source may refer to the source 170 or aningress NE 101 on the PPR 120. In an embodiment, the destination mayrefer to the destination 180 or the egress NE 110 on the PPR 120.

At step 906, the advertisement 500 comprising the PPR-ID 230 and theattributes 240 specified for a PPR 120 are transmitted to another NE inthe network 100. For example, Tx 340 transmits the advertisement 500comprising the PPR-ID 230 and the attributes 240 specified for a PPR 120that are transmitted to another NE in the network 100.

At step 909, a local forwarding database 343 is updated to include thePPR information 210 in association with the destination in response tothe NE 101-112 being identified in the PPR information 210. For example,local forwarding database 343 is updated in the memory 360 to includethe attributes 240 in association with the PPR-ID 230.

FIG. 10 is a method 1000 for implementing resource reservation andmaintenance on a PPR 120 according various embodiments of thedisclosure. In an embodiment, method 1000 may be performed by anintermediate NE 101-112 (referred to with reference to this method 1000as the first NE 101-112) in a network 100.

At step 1003, an advertisement 500 comprising PPR information 210describing a path from a source to a destination is received fromanother NE 101-112. For example, Rx 320 receives the PPR information 210from the central entity 175 or another NE 101-112. The PPR information210 includes a PPR-ID 230 and an attribute 240 associated with aresource to be reserved on the PPR 120. In an embodiment, the source mayrefer to the source 170 or an ingress NE 101 on the PPR 120. In anembodiment, the destination may refer to the destination 180 or theegress NE 110 on the PPR 120.

At step 1006, a local forwarding database 343 is updated to include thePPR information 210 in association with the destination or egress NE inresponse to the first NE 101-112 being identified in the PPR information210. For example, local forwarding database 343 is updated in the memory360 to include the attributes 240 in association with the PPR-ID 230.

At step 1009, the PPR 120 is provisioned at the first NE 101-112 basedon the attribute 240 in the PPR information 210. For example, theresource associated with the attribute 240 is reserved for the PPR 120by the first NE 101-112.

At step 1011, a node status 220 of the first NE 101-112 is updated toindicate whether the resource for the PPR 120 has been successfullyreserved according to the attribute 240 included in the PPR information220. For example, the network configuration module 335 is executed bythe processor 330 to update the node status 220 of the first NE 101-112to indicate whether the resource for the PPR 120 has been successfullyreserved according to the attribute 240 included in the PPR information220.

At step 1013, the node status 220 is transmitted to the central entity175. For example, Tx 340 transmits the node status 220 to the centralentity 175.

FIG. 11 shows an apparatus 1100 for implementing resource reservationand maintenance on a PPR 120 according various embodiments of thedisclosure. The apparatus 1100 comprises a means for receiving 1103, ameans for updating 1106, and a means for transmitting 1109. The meansfor receiving 1103 comprises a means to receive an advertisement 500comprising PPR information 210 describing a path from a source to adestination. The PPR information 210 includes a PPR-ID 230 and anattribute 240 associated with a resource to be reserved on the PPR 120.In an embodiment, the source may refer to the source 170 or an ingressNE 101 on the PPR 120. In an embodiment, the destination may refer tothe destination 180 or the egress NE 110 on the PPR 120. The means forupdating 1106 comprises a means to update a local forwarding database343 to include the PPR information 210 in association with thedestination. The means for transmitting 1109 comprises a means totransmit the advertisement 500 comprising the PPR-ID 230 and theattributes 240 specified for a PPR 120 to another NE 101-112 in thenetwork 100.

FIG. 12 shows an apparatus 1200 for implementing resource reservationand maintenance on a PPR 120 according various embodiments of thedisclosure. The apparatus 1200 comprises a means for receiving 1203, ameans for updating 1206, a means for provisioning 1209, and a means fortransmitting 1211. The means for receiving 1203 comprises a means toreceive an advertisement 500 comprising PPR information 210 describing apath from a source to a destination from another NE 101-112. The PPRinformation 210 includes a PPR-ID 230 and an attribute 240 associatedwith a resource to be reserved on the PPR 120. In an embodiment, thesource may refer to the source 170 or an ingress NE 101 on the PPR 120.In an embodiment, the destination may refer to the destination 180 orthe egress NE 110 on the PPR 120. The means for updating 1206 comprisesa means to update a local forwarding database 343 to include the PPRinformation 210 in association with the destination in response to theapparatus 1200 being identified in the PPR information 210. The meansfor provisioning 1209 comprises a means to provision the PPR 120 basedon the attribute 240 included in the PPR information 210. The means forupdating 1206 further comprises a means to update a node status 220 ofthe apparatus 1200 to indicate whether the resource for the PPR 120 hasbeen successfully reserved according to the attribute 240 included inthe PPR information 220. The means for transmitting 1211 comprises ameans to transmit the node status 220 to the central entity 175.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods might beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein. For example, the variouselements or components may be combined or integrated in another systemor certain features may be omitted, or not implemented.

In addition, techniques, systems, subsystems, and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown or discussed as coupled or directly coupled orcommunicating with each other may be indirectly coupled or communicatingthrough some interface, device, or intermediate component whetherelectrically, mechanically, or otherwise. Other examples of changes,substitutions, and alterations are ascertainable by one skilled in theart and could be made without departing from the spirit and scopedisclosed herein.

What is claimed is:
 1. A method implemented by a network element (NE) ina network, comprising: transmitting, to one or more other NEs in thenetwork, a node resource capability message including one or more flagsindicating each usage statistic that the NE is capable of monitoring fora resource reserved in the network; receiving, an advertisementcomprising preferred path route (PPR) information describing a path froman ingress NE to an egress NE in the network after transmitting the noderesource capability message, the PPR information comprising a PPRidentifier (PPR-ID) and an attribute associated with a resource to bereserved on the PPR; transmitting the advertisement comprising thePPR-ID and the attribute associated with the resource to be reserved onthe PPR to one or more other NEs in the network; updating a localforwarding database to include the PPR information in association withthe egress NE in response to the NE being identified in the PPRinformation; collecting the usage statistics of the resource, which theNE is capable of monitoring, after transmitting the node resourcecapability message and updating the local forwarding database to includethe PPR information, the usage statistics describing networkcharacteristics of the resource to be reserved on the PPR; andtransmitting the usage statistics of the resource to the one or moreother NEs in the network.
 2. The method of claim 1, wherein theattribute includes at least one of a bandwidth required to transmit adata packet along the PPR, a burst size permitted to be transmittedalong the PPR, a bounded latency permitted to occur on an NE along thePPR, or a lifetime indicating a time period during which the resource isto be reserved on each element of the PPR.
 3. The method of claim 2,further comprising: deleting the PPR information from the localforwarding database in response to determining that a state refreshincluding the PPR information has not been received by the NE within thetime period during which the resource is reserved; and removing areservation of the resource on the one or more NEs or links on the PPRin response to determining that the state refresh including the PPRinformation has not been received by the NE within the lifetime.
 4. Themethod of claim 1, further comprising receiving a state refresh from atleast one of a central entity of the network or a second NE in thenetwork, wherein the state refresh comprises the PPR information.
 5. Themethod of claim 1, further comprising: receiving, by the NE, amodification of the attribute associated with the resource reserved onthe PPR from at least one of a central entity of the network or a secondNE in the network; and updating, by the NE, the local forwardingdatabase based on the modification of the attribute received.
 6. Themethod of claim 1, further comprising determining, by the NE, that atleast one NE or link on the PPR fails to satisfy the attribute definedby the PPR information.
 7. The method of claim 1, further comprisingtransmitting a status to at least one of another NE or a central entityin the network using an underlying Interior Gateway Protocol (IGP) ofthe network, wherein the status indicates whether the resource has beensuccessfully reserved based on the attribute included in the PPRinformation.
 8. The method of claim 1, wherein the usage statistics arecollected periodically after reserving the resource for the PPR based onthe PPR information, and wherein the usage statistics comprises at leastone of a queue delay that occurs as a plurality of data packets aretransmitted from the NE to another NE on the PPR or bandwidth statisticsregarding at least one link coupled to the NE.
 9. A network element (NE)implemented in a network, comprising: a memory configured to storeinstructions; and a processor coupled to the memory and configured toexecute the instructions, which cause the processor to be configured to:transmit, to one or more other NEs in the network, a node resourcecapability message including one or more flags indicating each usagestatistic that the NE is capable of monitoring for a resource reservedin the network; receive an advertisement comprising preferred path route(PPR) information describing a path from an ingress NE to an egress NEin the network after transmitting the node resource capability message,the PPR information comprising a PPR identifier (PPR-ID) and anattribute associated with a resource to be reserved on the PPR; transmitthe advertisement comprising the PPR-ID and the attribute associatedwith the resource to be reserved on the PPR to the one or more other NEsin the network; update a local forwarding database to include the PPRinformation in association with the egress NE; collect the usagestatistics of the resource, which the NE is capable of monitoring, aftertransmitting the node resource capability message and updating the localforwarding database to include the PPR information, the usage statisticsdescribing network characteristics of the resource to be reserved on thePPR; and transmit the usage statistics of the resource to the one ormore other NEs in the network.
 10. The NE of claim 9, wherein theattribute includes at least one of a bandwidth required to transmit adata packet along the PPR, a burst size permitted to be transmittedalong the PPR, a bounded latency permitted to occur on an NE along thePPR, or a lifetime indicating a time period during which the resource isto be reserved on each element of the PPR.
 11. The NE of claim 10,wherein the instructions further cause the processor to be configuredto: delete the PPR information from the local forwarding database inresponse to determining that a state refresh including the PPRinformation has not been received by the NE within the time periodduring which the resource is reserved; and remove a reservation of theresource on the one or more NEs or links on the PPR in response todetermining that the state refresh including the PPR information has notbeen received by the NE within the lifetime.
 12. The NE of claim 9,wherein the instructions further cause the processor to be configured toreceive a state refresh from at least one of a central entity of thenetwork or a second NE in the network, wherein the state refreshcomprises the PPR information.
 13. The NE of claim 9, wherein theinstructions further cause the processor to be configured to: receive amodification of the attribute associated with the resource reserved onthe PPR from at least one of a central entity of the network or a secondNE in the network; and update the local forwarding database based on themodification of the attribute received.
 14. The NE of claim 9, whereinthe instructions further cause the processor to be configured todetermine that at least one NE or link on the PPR fails to satisfy theattribute defined by the PPR information.
 15. The NE of claim 9, whereinthe instructions further cause the processor to be configured totransmit a status to at least one of another NE or a central entity inthe network using an underlying Interior Gateway Protocol (IGP) of thenetwork, wherein the status indicates whether the resource has beensuccessfully reserved based on the attribute included in the PPRinformation.
 16. A non-transitory computer readable medium configured tostore a computer program product comprising computer executableinstructions that, when executed by a processor of a network element(NE) implemented in a network, cause the processor to: transmit, to oneor more other NEs in the network, a node resource capability messageincluding one or more flags indicating each usage statistic that the NEis capable of monitoring for a resource reserved in the network; receivean advertisement comprising preferred path route (PPR) informationdescribing a path from an ingress NE to an egress NE in the networkafter transmitting the node resource capability message, the PPRinformation comprising a PPR identifier (PPR-ID) and an attributeassociated with a resource to be reserved on the PPR; transmit theadvertisement comprising the PPR-ID and the attribute associated withthe resource to be reserved on the PPR to the one or more other NEs inthe network; update a local forwarding database to include the PPRinformation in association with the egress NE in response to the NEbeing identified in the PPR information; collect the usage statistics ofthe resource, which the NE is capable of monitoring, after transmittingthe node resource capability message and updating the local forwardingdatabase to include the PPR information, the usage statistics describingnetwork characteristics of the resource to be reserved on the PPR; andtransmit the usage statistics of the resource to one or more other NEsin the network.
 17. The non-transitory computer readable medium of claim16, wherein the attribute includes at least one of a bandwidth requiredto transmit a data packet along the PPR, a burst size permitted to betransmitted along the PPR, a bounded latency permitted to occur on an NEalong the PPR, or a lifetime indicating a time period during which theresource is to be reserved on each element of the PPR.
 18. Thenon-transitory computer readable medium of claim 17, wherein thecomputer executable instructions further cause the processor to: deletethe PPR information from the local forwarding database in response todetermining that a state refresh including the PPR information has notbeen received by the NE within the time period during which the resourceis reserved; and remove a reservation of the resource on the one or moreNEs or links on the PPR in response to determining that the staterefresh including the PPR information has not been received by the NEwithin the lifetime.
 19. The non-transitory computer readable medium ofclaim 16, wherein the computer executable instructions further cause theprocessor to receive a state refresh from at least one of a centralentity of the network or a second NE in the network, wherein the staterefresh comprises the PPR information.
 20. The non-transitory computerreadable medium of claim 16, wherein the computer executableinstructions further cause the processor to determine that at least oneNE or link on the PPR fails to satisfy the attribute defined by the PPRinformation.